Jecker Horizontal Catoptric Microscope

This novel horizontal microscope is a part of the collection belonging to the Department of Physics at the University of Naples in Italy. The microscope is autographed "Jecker á Paris", and is believed to have been manufactured by Paris scientific instrument maker Francois-Antoine Jecker in the early to middle nineteenth century.

The most unusual feature of this microscope is the catoptric concave mirror used in image formation to reduce the effects of aberration in the objective. The eyepiece is positioned at one end of the horizontal body tube, while the mirror is placed at the opposite end (at the left end in the illustration above). Image-forming light rays enter the objective and are directed into the concave mirror by means of a plane mirror placed directly above the objective mount. These light rays then form an image at the primary image plane in the eyepiece. The body tube is supported by two tubular bars on a wooden case that also serves as a storage compartment for accessories. The stage is positioned beneath the objective and focusing is accomplished with a rack attaching the stage to one of the support bars. On the same bar is a small reflecting mirror to assist in transmitted light illumination.